1. Technical Field
The present invention relates to an ultrasonic diagnosis apparatus, and more particularly to a technique of reducing an unnecessary or undesired signal component in a reception, signal.
2. Background Art
Ultrasonic diagnosis apparatuses are apparatuses which form an ultrasonic diagnosis image by transmitting and receiving ultrasound to and from a living organism. In order to increase the image quality of the ultrasonic diagnosis image, it is desirable to reduce an unnecessary signal component contained in a reception signal; i.e., a side-lobe component, a grating lobe component, a noise component, or the like.
Two methods have been proposed for reducing or suppressing an unnecessary signal component contained in a reception signal after phase alignment and summing processing: one is a first method (a GCF method) for suppressing a reception signal by using a factor called a GCF (Generalized Coherence Factor) (see Pai-Chi Li, et al, “Adaptive Imaging Using the Generalized Coherence Factor”, IEEE Transactions Ultrasonics, Vol. 50, No. 2, 2003), and the other is a second method (an SCF method) for suppressing a reception signal by using a factor called an SCF (Sign Coherence Factor) (see J. Camacho, et al, “Phase Coherence Imaging”, IEEE trans. UFFC, vol. 56, No. 5, 2009 (WO2010/018282)).
However, both methods described above have advantages and disadvantages. From a viewpoint of enhancement of the image quality of an ultrasonic diagnosis image, it has been desired to prevent excessive suppression of a main-lobe component while effectively suppressing an unnecessary signal component such as a side-lobe component.